The chart I posted matches the Technik documents issued by the Factory. I will have to double check silver but I do have 2 sources saying it is special order. Here is one Adrian's book is another
http://members.rennlist.com/jfk964/color_options.htm
The technik info is usually published at the beginning of production so it is not always correct since Porsche has been known to make changes. Although I have a sales book published by PCNA as a guide to the sales people and it says Polar silver was standard and Zermatt was Special order. But I found several things incorrectly published in this book.
A8 would be the internal paint code not the one used to order paint. You would use 92E or 92M (WB) to order polar silver paint. Although most info is usually flawed. The link I posted doesn't have cobalt blue as a special order for 1994 yet my car is and I know of 2 others panted in cobalt.
Adrian Streather has 15 standard colors and 47 special order paints with your options 998 special order from previous 911 series and 999 special order color sample provided by customer. So it is hard to know the absolute truth sometimes.